The pupillary light reflex (PLR) is a reflex that controls the diameter of the pupil, in response to the intensity of light that falls on the retinal ganglion cells of the retina in the back of the eye, thereby assisting in adaptation to various levels of lightness/darkness. A greater intensity of light causes the pupil to constrict, whereas a lower intensity of light causes the pupil to dilate. Thus, the pupillary light reflex regulates the intensity of light entering the eye. It is well documented in the medical and scientific community that an individual PLR may be altered by ingesting or otherwise introducing an intoxicating substance, such as alcohol or a drug, or by a medical condition such as a concussion or by other neurological disorders such as diabetic neuropathy. Thus, the analysis of the PLR can be used to detect impairment due to intoxicating substances and/or all neurological disorder affecting an individual PLR response.
Impairment can be brought about by or the result of ingesting or otherwise introducing an intoxicating substance, such as alcohol or a drug, a neurological disorder can be caused by a medical condition such as a concussion or by other pathologies like diabetic neuropathies. By impairment it is meant a diminution of a speed or quality in mental and motor functions of the effected individual. Impairment can include or result in loss or diminishment in judgment, self-control, reasoning, memory, speech and/or coordination. By neurological disorder is meant any disorder of the nervous system.
Extreme impairment is readily recognizable to others, and, generally, to the individual—although because judgment is impaired the individual may not recognize or acknowledge the impairment. More problematic are situations in which the individual is only mildly impaired and thus may not be aware of any impairment at all. For example, because of a multitude of factors that affect blood alcohol concentration, i.e., age, gender, rate of consumption, body mass, food consumption and alcohol intolerance common among some ethnic groups, it is very difficult for an individual to assess his or her own impairment. While earlier stages of alcohol impairment may be undetectable to the drinker and others, it is known even small amounts of alcohol may affect one's ability to drive, and a person will possibly be too impaired to drive or perform a dangerous task before appearing or maybe even feeling “drunk” or “high.”
The same situation can arise when a person has suffered a blow to the head and have a concussion or is suffering from extreme fatigue, but insist that they ‘feel fine,’ and do not require medical attention or rest.
Chronic illnesses like diabetes are known to cause diabetic neuropathies that alter the PLR response over time. People with diabetes can, over time, develop nerve damage throughout the body. The change is subtle and slow and some people with nerve damage have no symptoms.
Thus, there is a need for an easy to use, portable and ubiquitous system and method to permit a person to measure the Pupillary Light Reflex response in themselves and others and correlate such measurement to a degree of impairment due to the assumption of impairing substances and/or to a neurological disorder for diagnostic, screening, authorization and/or monitoring purposes.